# Tag Info

1

Here's a piece of the schematic for that, found here (Thanks, @GodJihyo). I've added in the resistor in red. That choke is not there to provide clean DC to the final transistor. It's there to isolate the DC supply from the RF on the collector of that final transistor. Ideally it provides a perfect path for DC, and perfect isolation for AC. In reality, ...

1

What might be this resistor's purpose? I've used a resistor in parallel with an inductor on a noisy rail rolling stock power supply to get rid of as much ripple and transient rubbish as possible. The basic idea is the resistor (along with a smoothing capacitor after the resistor) form a good low-pass filter. However, that low-pass is no good for passing ...

2

Just set up a current source of 1 A with a parallel inductor and read the DC voltage. Even better, use the same current source but in an .AC analysis (of several decades). It should be more than sufficient to determine whether there are poles or zeroes.

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I had soldered the inductor to the PCB with jumper wires so that I could test different inductors out trying to understand how different inductors would impact the performance of the boost converter. @cyclone mentioned in a comment that the jumper wires were likely the cause of my issues and that was correct! Once I started soldering the inductors to the ...

0

The way to modify the airgap reluctance is to change its width, either by squeezing the pole pieces together (or stretching them apart), or inserting some ferromagnetic material. Decreasing the gap will reduce reluctance, increasing it will increase reluctance. Indeed if you attempt to measure the changes in permeability of the air itself (e.g. using ...

2

The relative permeability of air is about 1.0000004. A stream of air will decrease air pressure (Bernoulli principle) and thus slightly lower the relative permeability. But clearly this can only change within the range of 1.0000004 to 1 (vacuum) which is a change that is likely not detectable.

3

Saying resistive, capacitive, or inductive just means which behaviour is dominant. It's not a precise term and one of those things students might try too hard to ascribe precise formal definition to when it is inappropriate. In my opinion it is rather unimportant. Things are what they are with varying shades of grey. So just combine Xc and XL since they ...

1

TOPSWITCH application notes can be a great source of help. I think in AN-16 they explain how you determine the turn ratio.

4

Inductor rationalisation for BOM consolidation can and does reduce manufacturing costs . If you use a larger value than recommended the ripple current is lower but you can sometimes get instability on these jellybean peak current mode hardswitch chips . check for this ,you may have to delve into the control loop .

1

From page 14 of the datasheet. Your temperature rise is much higher than expected so I'd check that you're not saturating the inductor. A 65°C temperature rise above ambient suggests that you're running at 7.5 A. The DC resistance is listed as 40.8 mΩ. 7.5 A will cause a dissipation of $P = I^2R = 7.5^2 \times 0.04 = 2.25\ \text W$.

2

It looks like the op-amp is limiting current, max should be 20 mA. You have tried with gain=1 with same result, so resolver impendance is below 80 Ohm. You need more current output. An audio amplifier can handle 4 Ohm, so maybe a good choice.

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I can see that it is tempting to use an EMC common mode choke. I would not because the DC current rating of the choke is very low due to core saturation and often the ferrite is more lossey which is good for EMC but not as the main inductor of a SMPS. Also the common mode EMC chokes have significant leakage inductance which is generaly undesirable on hard ...

2

That schematic you have there is a bit ambiguous: it uses an on/off switch for the series element, but a diode for the parallel one. If the diode would have been drawn as another switch, then things would have been clearer (I hope): simulate this circuit – Schematic created using CircuitLab When SW2 is closed, the inductor is connected to ground with ...

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The average inductor voltage should be zero which means that V-sec of the inductor voltage should be balanced. As per your your derivation it is not true.. Volt-sec in Ton must be equal to Toff.. Therefore, it should be => ton(Vin-Vout)+toff(-Vout)=0 => Vin(ton)= Vout(T) => Vin/Vout = ton/T

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The way you have defined your current $V_L = -L \frac{dI_L}{dt}$ for the conventional $V = L \frac{dI}{dt}$ the current I flows INTO the positive terminal of the inductor.

3

I am having trouble with what frequency I should use to convert inductors and/or capacitors to their corresponding impedances in the frequency domain (i.e. what omega to plug-in in jwL and j/wC). If you are doing AC analysis (assuming the behavior is linear when driven by a small AC excitation around a DC operating point), then you will do two steps. First ...

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You have to use the frequency corresponding to the voltage source that you're computing the values for. That is, when you calculate the currents and voltage drops caused by the DC source, all capacitors are open-circuit and inductors are short-circuit. Then when you do the same for an AC source, you replace the caps and inductors with the impedance they have ...

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You are correct. The collapsing magnetic field is what provides the energy to the inductive kick.

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